Row driver circuitry for imaging devices and related method of operation

Abstract

Row drivers as a part of an image sensor device include circuitry for supplying a plurality of signals with an increased voltage and enhanced reliability to a corresponding row in a pixel array. The row driver circuitry is designed to input a signal such as row select, reset or transfer and additionally input a boosted voltage supply. The row select, reset, or transfer signal is then output with a boosted voltage that is higher than the operating voltage supply. The row driver circuit is configured so that all terminal voltages across any of the plurality of transistors within the row driver circuit are less than or equal to the operating voltage supply.

1. A row driver circuit, comprising:
 a voltage supply; 
 a boosted voltage supply comprising a voltage that is larger than the voltage supply by a boosted amount; 
 a pre-driver operably coupled to the voltage supply and configured to generate a driver voltage that is at least the boosted amount above a reference voltage, wherein the pre-driver is further configured to receive an input signal; 
 a first transistor operably coupled in series between a second transistor and a ground voltage, wherein a gate of the first transistor is configured to receive the input signal, wherein the second transistor is operably coupled in series between the first transistor and an output signal, wherein the second transistor is configured to conduct and generate a drain-to-source voltage drop of at least the boosted amount; and 
 a third transistor operably coupled between the boosted voltage supply and the output signal, wherein a gate of the third transistor is configured to receive the driver voltage. 
 
   
   
     2. The row driver circuit of  claim 1 , wherein the reference voltage is equal to the ground voltage. 
   
   
     3. The row driver circuit of  claim 1 , wherein the first transistor and the second transistor are NMOS transistors. 
   
   
     4. The row driver circuit of  claim 1 , wherein the third transistor is a PMOS transistor. 
   
   
     5. The row driver circuit of  claim 1 , wherein the pre-driver is further configured to receive a second input signal configured as a logical opposite of the input signal. 
   
   
     6. The row driver circuit of  claim 1 , wherein the pre-driver comprises a second PMOS transistor in series with a third PMOS transistor, a drain of the second PMOS transistor operably coupled to the ground voltage, the source of the third PMOS transistor operably coupled to the voltage supply. 
   
   
     7. The row driver circuit of  claim 1 , wherein the first, second and third transistors include a plurality of terminal voltages between any two terminals of a gate, a source, and a drain, wherein each of the plurality of terminal voltages is less than or equal to the voltage supply. 
   
   
     8. The row driver circuit of  claim 1 , wherein the input signal is selected from the group consisting of row select, reset and transfer. 
   
   
     9. A method of operating a row driver circuit, comprising:
 inputting a voltage supply to a pre-driver; 
 inputting an input signal to the pre-driver; 
 generating a driver voltage from the pre-driver that is at least a boosted amount above a reference voltage; 
 generating an output signal, the generating comprising:
 inputting the input signal into a gate of a first transistor; 
 supplying a boosted voltage to a source of a third transistor, a drain of the third transistor operably coupled to an output node; 
 wherein the boosted voltage is larger than the voltage supply by the boosted amount; 
 configuring a second transistor to conduct and generate a drain-to-source voltage drop of at least the boosted amount, the second transistor operably coupled to the output node; and 
 operably coupling the driver voltage to a gate of the third transistor. 
 
 
   
   
     10. The method of  claim 9 , wherein the reference voltage is a ground voltage. 
   
   
     11. The method of  claim 9 , wherein the first, second and third transistors comprise a plurality of terminal voltages, wherein each of the plurality of terminal voltages is less than or equal to the voltage supply. 
   
   
     12. The method of  claim 9 , wherein generating a driver voltage comprises generating a voltage that is between a voltage substantially near a threshold voltage of a p-channel transistor and a voltage substantially near the voltage supply. 
   
   
     13. The method of  claim 9 , further comprising inputting a second input signal configured as a logical opposite of the input signal. 
   
   
     14. The method of  claim 9 , wherein inputting the input signal comprises inputting a signal selected from the group consisting of row select, reset and transfer. 
   
   
     15. A method of operating a row driver circuit, comprising:
 inputting a voltage supply to a pre-driver; 
 inputting an input signal to the pre-driver; 
 generating a driver voltage from the pre-driver that is at least a boosted amount above a ground voltage; 
 generating a boosted voltage on an output signal when the input signal is negated; 
 generating a voltage that is substantially near the ground voltage on the output signal when the input signal is asserted; and 
 transitioning the output signal between a first voltage state and a second voltage state responsive to the driver voltage, wherein the driver voltage is independent from the output signal. 
 
   
   
     16. A method of operating a row driver circuit, comprising:
 inputting a voltage supply to a pre-driver; 
 inputting an input signal to the pre-driver; 
 generating a driver voltage from the pre-driver that is at least a boosted amount above a reference voltage; 
 generating a boosted voltage on an output signal when the input signal is negated by adjusting the boosted voltage by the boosted amount; 
 generating a voltage that is substantially near a ground voltage on the output signal when the input signal is asserted; and 
 transitioning the output signal between a first voltage state and a second voltage state responsive to the driver voltage, wherein the driver voltage is independent from the output signal. 
 
   
   
     17. The method of  claim 16 , further comprising inputting a second input signal configured as a logical opposite of the input signal. 
   
   
     18. A method of operating a row driver circuit, comprising:
 inputting a voltage supply to a pre-driver; 
 inputting an input signal to the pre-driver; 
 generating a driver voltage from the pre-driver that is at least a boosted amount above a reference voltage, wherein the driver voltage is between a voltage substantially near a threshold voltage of a p-channel transistor and a voltage substantially near the voltage supply; 
 generating a boosted voltage on an output signal when the input signal is negated; 
 generating a voltage that is substantially near a ground voltage on the output signal when the input signal is asserted; and 
 transitioning the output signal between a first voltage state and a second voltage state responsive to the driver voltage, wherein the driver voltage is independent from the output signal. 
 
   
   
     19. The method of  claim 18 , wherein inputting the input signal comprises inputting a signal selected from the group consisting of row select, reset and transfer. 
   
   
     20. An image sensor device, comprising:
 an array of pixels arranged on a semiconductor device, wherein each pixel is configured for sensing light incident on the pixel; 
 a row driver circuit, comprising:
 a voltage supply; 
 a boosted voltage supply comprising a voltage that is larger than the voltage supply by a boosted amount; 
 a pre-driver operably coupled to the voltage supply and configured to generate a driver voltage that is at least the boosted amount above a reference voltage, wherein the pre-driver is further configured to receive an input signal; 
 a first transistor operably coupled in series between a second transistor and a ground voltage, wherein a gate of the first transistor is configured to receive the input signal, wherein the second transistor is operably coupled in series between the first transistor and an output signal, wherein the second transistor is configured to conduct and generate a drain-to-source voltage drop of at least the boosted amount; 
 a third transistor operably coupled between the boosted voltage supply and the output signal, wherein a gate of the third transistor is configured to receive the driver voltage; and 
 
 a plurality of buses, each bus coupled to the pixels in a row of the pixel array and configured to carry the output signal. 
 
   
   
     21. The image sensor device of  claim 20 , wherein the reference voltage is equal to the ground voltage. 
   
   
     22. The image sensor device of  claim 20 , wherein the first transistor and the second transistor are NMOS transistors. 
   
   
     23. The image sensor device of  claim 20 , wherein the third transistor is a PMOS transistor. 
   
   
     24. The image sensor device of  claim 20 , wherein the pre-driver is further configured to receive a second input signal configured as a logical opposite to the input signal. 
   
   
     25. The image sensor device of  claim 20 , wherein the pre-driver comprises a second PMOS transistor in series with a third PMOS transistor, a drain of the second PMOS transistor operably coupled to the ground voltage, a source of the third PMOS transistor operably coupled to the voltage supply. 
   
   
     26. The image sensor device of  claim 20 , wherein the first, second and third transistors include a plurality of terminal voltages between any two terminals of a gate, a source, and a drain, wherein each of the plurality of terminal voltages is less than or equal to the voltage supply. 
   
   
     27. The image sensor device of  claim 20 , wherein the input signal is selected from the group consisting of row select, reset and transfer.